Decomposition of cellulose by continuous near-critical water reactions

A pilot-scale apparatus for continuous supercritical and near-critical wate r reaction was set up. A high-pressure slurry supplying system was develope d to feed the solid material-water slurries. The apparatus features tempera ture up to 600 degreesC, pressure up to 40 MPa, residence time from 24 s to 15 min, maximum amount of slurry supply of 2.4 L.h(-1), maximum solid cont ent of slurry up to 10% (by mass) for cellulose from Merck, and resistance to corrosion. Long-time runs of decomposition of cellulose were carried out and steady runs were confirmed. Kinetics of cellulose decomposition was st udied. The apparent activation energy evaluated was 147 kJ.mol(-1). In addi tion, a new three-step pathway for cellulose hydrolysis was proposed. The d erived kinetic equation is in good agreement with the experimental data.